1. Field of the Invention
The present invention relates to a multi-light emitting diode (multi-LED) package, and more particularly to a multi-LED package to simultaneously or individually emit different colors of light including white, infrared or ultraviolet.
2. Description of the Related Art
Generally, an LED package includes an LED chip, a lead frame through which electric current is applied to the LED chip, and a housing for supporting the lead frame. In recent years, attention to LED package-based lightings has rapidly increased. To apply the LED package to lightings, improved luminescence and a high optical output of 1,000's of lumens or more are sought. Since output luminescence is proportional to the amount of input current, a desired optical output can be obtained by supplying a high electric current to the LED chip. However, this increase in input current may generate excessive heat.
Further, if the heat is not dissipated from the LED package, the heat may cause dislocations and mismatches in a semiconductor crystal of the LED chip, thereby reducing a service life of the LED chip. Hence, a heat sink is provided to the LED package as a heat absorption or dissipation source.
The LED package may include a plurality of LED chips mounted on a heat sink formed of a single heat dissipation slug to emit light of different wavelengths such that the LED chips can be individually operated to emit multiple colors. In general, a red LED chip, a green LED chip, and a blue LED chip are mounted together in a single LED package to emit plural colors by operating the LED chips in an individual manner or in combination. One example of this technique is disclosed in Korean Patent No. 0558082 issued to this application's Assignee.
However, if the LED chips for emitting red, green and blue colors are mounted together in the single LED package, all of the LED chips are operated to emit white light. Accordingly, it is difficult for the LED package to adjust the balance between colors.
Additionally, since an LED chip for emitting white light includes a phosphor, there are many difficulties in mounting the white LED chip and other LED chips for emitting different colors in a single LED package.
Furthermore, to achieve individual operation of the LED chips on a single heat dissipation slug made of a conductive metal, the LED chips have been lateral-type LED chips that are electrically insulated from the heat dissipation slug, and each LED chip is electrically wired by a two-bonding method in which the LED chip is connected to two lead-frames via two bonding wires. Therefore, for a vertical-type LED chip having an electrode disposed on the bottom of the LED chip and electrically connected to the heat dissipation slug, application thereof to such an LED package as described above is difficult.